Cardiac Electrical System

​Cardiac Conduction System

By Tristan Dimmick

Multiple Choice

During which part of the EKG does the AV node delay occur?

• Before the P wave

• Between the P wave and QRS complex

• During the QRS complex

• After the T wave

Multiple Choice

The S1 heart sound (“lub”) occurs at which point in the cardiac cycle?

• During the P wave

• During the QRS complex

• During the T wave

• Just before atrial depolarization

Multiple Choice

What would happen if the AV node did not delay the electrical signal?

• Atria and ventricles would contract at different rates

• Atria and ventricles would contract simultaneously

• Ventricles would contract too late

• Heart rate would decrease significantly

Multiple Choice

Which portion of the conduction system directly causes ventricular contraction?

• AV node

• Bundle of His

• Purkinje fibers

• SA node

Multiple Choice

During ventricular systole, which heart valves are open?

• Mitral and tricuspid

• Pulmonary and aortic 

• All valves

• None of the valves

Multiple Choice

The T wave on an EKG corresponds to which physiological process?

• Atrial contraction

• Atrial relaxation

• Ventricular contraction

• Ventricular relaxation

Multiple Choice

Which event occurs immediately after the T wave?

• Ventricular contraction

• Atrial contraction

• Ventricular contraction

• AV node delay

Multiple Choice

Which event would most directly cause the S2 (“dub”) heart sound?

• Closure of atrioventricular valves

• Closure of semilunar valves 

• Contraction of the ventricles

• Contraction of the atria

Multiple Choice

Which of the following structures is active during the P wave?

• Atrioventricular node

• Bundle of His

• Purkinje fibers

• Sinoatrial node